Novel solvents for the catalytic process for producing polyhydric alcohols

ABSTRACT

This invention relates to the manufacture of polyhydric alcohol(s) by the reaction of synthesis gas in the presence of a rhodium carbonyl complex dissolved in a substituted gamma-butyrolactone solvent.

This invention relates to an improved process for the manufacture ofpolyhydric alcohols, in particular alkane polyols, as well as a varietyof other chemicals, in particular methanol, from synthesis gas, i.e., amixture of carbon monoxide and hydrogen.

Specifically, this invention is directed to an improved process ofmaking alkane diols, triols, tetraols, etc., containing 2, 3, 4 or morecarbon atoms. A key product of the process of this invention is ethyleneglycol. Byproducts of this invention are the lesser valuable, butnonetheless valuable, monohydric alkanols such as methanol, and ethanol.The products of the process of this invention contain carbon, hydrogenand oxygen.

There are described in U.S. Pat. No. 3,833,634 issued Sept. 3, 1974, andU.S. Pat. No. 3,957,857, issued May 18, 1976, processes for reactinghydrogen and oxides of carbon in the presence of rhodium carbonylcomplex catalysts. The conditions employed in those processes involvereacting a mixture of an oxide of carbon and hydrogen with a catalyticamount of rhodium in a complex combination with carbon monoxide, at atemperature of between about 100° C. and about 375° C. and a pressure ofbetween about 500 p.s.i.a. and about 50,000 p.s.i.a. In addition to theaforementioned U.S. Patents, the following U.S. Patents and U.S. Patentapplications amplify the development of the process for making alkanepolyols from mixtures of hydrogen and oxides of carbon:

U.S. Pat. No. 3,878,292--Patented Apr. 15, 1975

U.S. Pat. No. 3,878,290--Patented Apr. 15, 1975

U.S. Pat. No. 3,878,214--Patented Apr. 15, 1975

U.S. Pat. No. 3,886,364--Patented May 27, 1975

U.S. Pat. No. 3,940,432--Patented Feb. 24, 1976

U.S. Pat. No. 3,929,969--Patented Dec. 30, 1976

U.S. Pat. No. 3,952,039--Patented Apr. 20, 1976

U.S. Pat. No. 3,948,965--Patented Apr. 6, 1976

U.S. Pat. No. 3,944,588--Patented Mar. 16, 1976

U.S. Pat. No. 3,957,857--Patented May 18, 1976

U.S. Pat. No. 3,974,259--Patented Aug. 10, 1976 (formerly U.S. Ser. No.455,380, filed Mar. 27, 1974)

U.S. Pat. No. 3,989,799--Patented Nov. 2, 1976 (formerly U.S. Ser. No.455,379, filed Mar. 27, 1974)

U.S. Pat. No. 4,013,700--Patented Mar. 22, 1977 (formerly U.S. Ser. No.526,942, filed Nov. 25, 1974)

U.S. Ser. No. 488,139--Filed July 12, 1974 (now abandoned)

U.S. Ser. No. 506,862--Filed Sept. 17, 1974 (now abandoned)

U.S. Pat. No. 4,001,289--Patented Jan. 4, 1977 (formerly U.S. Ser. No.506,864, filed Sept. 17, 1974)

U.S. Ser. No. 506,865--Filed Sept. 17, 1974 (now abandoned)

U.S. Ser. No. 615,093--Filed Sept. 19, 1975

U.S. Ser. No. 537,885--Filed Jan. 2, 1975 (now abandoned)

U.S. Ser. No. 618,023--Filed Sept. 30, 1975 (now abandoned)

U.S. Ser. No. 618,061--Filed Sept. 30, 1975 (now abandoned)

U.S. Ser. No. 618,021--Filed Sept. 30, 1975

U.S. Ser. No. 727,646--Filed Sept. 29, 1976 (now abandoned)

U.S. Ser. No. 782,986--Filed Mar. 30, 1977 (now U.S. Pat. No. 4,111,975,patented Sept. 5, 1978).

Also, U.S. Pat. No. 3,968,136 patented July 6, 1976 describes a processfor producing alkane polyols from mixtures of hydrogen and oxides ofcarbon in the presence of a rhodium carbonyl complex dissolved in asolvent selected from gamma-butyrolactone and delta-valerolactone at atemperature of between about 100° C. and about 375° C. and a pressurebetween about 1000 and about 50,000 psig.

The gamma-butyrolactone and delta-valerolactone solvents as described inU.S. Pat. No. 3,968,136 are good solvents for the production of alkanepolyols from synthesis gas. However, under the reaction conditions whichproduce the alkane polyols, it is postulated that the aforedescribedlactone solvents react with the hydroxylic compounds present therein.This is based on the fact that gamma-butyrolactone reacts with water andalcohols. The equilibrium constant, K, for the reaction ofgamma-butyrolactone with water and also, the rate constant, k, forsaponification of gamma-butyrolactone have been measured.

The equilibrium constant, K, measured at 25° C. is 35 M⁻¹ for thefollowing reaction:

gamma-butyrolactone+H₂ O⃡hydroxyacid [O. H. Wheeler and E. E. Grandell deRodriguez, Journal of Organic Chemistry, 29, 1227 (1964)].

The rate constant, k, for the saponification of gamma-butyrolactone in asolution of 92 percent ethanol at 25° C. is 0.047 M⁻¹ Sec⁻¹ [O. H.Wheeler and D. S. Gamble, Journal of Organic Chemistry, 26, 3221(1961)].

Thus, if the gamma-butyrolactone solvent reacts with the hydroxyliccompounds produced in the reaction of synthesis gas in the presence ofrhodium carbonyl complexes, the gamma-butyrolactone solvent must becontinually provided to the reaction to make up for this solvent loss.

The equilibrium constant, K, and the rate constant, k, for asubstituted-gamma-butyrolactone of the present invention, i.e., 2,2-dimethyl-gamma-butyrolactone, are<1.0 and 0.013, respectively. Thesevalues indicate that the substituted-gamma-butyrolactone would be lessreactive with hydroxylic compounds.

Also, it has been discovered that when thesubstituted-gamma-butyrolactone solvent of the present invention is usedwith a co-solvent, there is an improvement, both in the rate ofproduction of alkane diols and retention of rhodium in solution. Theretention of rhodium in solution is quite important since rhodium is anextremely expensive metal; it currently has a dealer's price of about$525 per troy ounce, so that it is particularly desirable to minimizeany loss of such rhodium values during the course of the reaction.Additionally, when the substituted-gamma-butyrolactone solvents of thepresent invention are used with a co-solvent, their stability underreaction conditions is much greater than that of gamma-butyrolactonesolvent.

The process of the present invention involves the production ofpolyhydric alcohol(s) by reacting in a solvent comprising substitutedgamma-butyrolactone at a pressure between about 1000 psig and 50,000psig and a temperature between about 100° C. and 375° C., oxides ofcarbon and hydrogen in the presence of a rhodium carbonyl complex.

The substituted-gamma-butyrolactone solvents of the present inventionare prepared according to the following procedure, which illustrates thepreparation of 2,2-dimethyl-gamma-butyrolactone: ##STR1## (as describedby H. E. Baumgarten and D. C. Gleason, Journal of Organic Chemistry, 16,1658, 1951) ##STR2## Reaction (2) is catalyzed by RuCl₂(triphenylphosphine)₃. (Reaction (2) is described by R. Morand & M.Kayser, Chemical Communications, p. 314 1976.)

The substituted gamma butyrolactone solvents of the present inventionare characterized by the following formula: ##STR3## wherein R₁ throughR₄ is at least one of hydrogen, straight or branched chain alkyl,preferably having from 1 to 12 carbon atoms, most preferably 1 to 6carbon atoms in the alkyl chain, such as methyl, ethyl, isopropyl,butyl, octyl, dodecyl and the like; a cycloaliphatic group including themonocyclic and bicyclic groups such as cyclopentyl, cyclohexyl, bicyclo[2.2.1] heptyl, and the like; or an aryl, alkaryl, or aralkyl group suchas phenyl, naphthyl, xylyl, tolyl, benzyl, beta-phenylethyl and thelike; an ether of the formula (O--R°) wherein R° may be aryl or loweralkyl having from 1 to 12 carbon atoms, preferably 1 to 4 carbon atomsin the alkyl chain; and alkylene or polyalkylene ether of the formula--OC_(n) H_(2n) _(x) OR°° wherein n has an average value of from 1 toabout 4, x has an average value of from 1 to about 150, preferably 1 toabout 20, most preferably 1 to about 4, and R°° may be alkyl having from1 to 6 carbon atoms in the alkyl chain, such as poly(oxyethylene),poly(oxypropylene), poly(oxyethylene-oxypropylene), alkyl ethers ofalkylene and polyalkylene glycols; ##STR4## wherein y may have any valuebetween 0 and 12 and R°°° may be a lower alkyl group having from 1 to 12carbon atoms, preferably from 1 to 4 carbon atoms, or aryl; providedthat one of R₁ or R₂ is other than hydrogen.

Preferably, the substituted-gamma-butyrolactone solvent used in thepractice of the present invention is 2,2-di(alkyl)substituted-gamma-butyrolactone, wherein the alkyl group contains 1 to12 carbon atoms, and preferably 1 to 6 carbon atoms. The most preferred2,2-di(alkyl)-gamma-butyrolactone solvent is2,2-dimethyl-gamma-butyrolactone.

Illustrative co-solvents which are generally suitable for use with thesubstituted gamma-butyrolactone solvents herein include, for example,ethers such as tetrahydrofuran, tetrahydropyran, diethyl ether,1,2-dimethoxybenzene, 1,2-diethoxybenzene, the dialkyl ethers ofethylene glycol, of propylene glycol, of butylene glycol, of diethyleneglycol, of dipropylene glycol, of triethylene glycol, of tetraethyleneglycol, of dibutylene glycol, of oxyethylene propylene glycol, etc;ketones such as acetone, methyl ethyl ketone, cyclohexanone,cyclopentanone, etc.; esters such as methyl acetate, ethyl acetate,propyl acetate, butyl acetate, methyl propionate, ethyl butyrate, methyllaurate, etc.; substituted and unsubstitutedtetrahydrothiophene-1,1-dioxides (sulfolanes) as disclosed in U.S. Ser.No. application 537,885, filed on Jan. 2, 1975, the disclosure at pages6 and 7 of the specification of which is incorporated herein byreference; butyrolactone as described in U.S. Pat. No. 3,968,136, whichis incorporated herein by reference.

Also, the crown ethers are suitable co-solvents herein, particularlythose as described in U.S. patent application Ser. No. 832,384 filedSept. 13, 1977, now U.S. Pat. No. 4,162,261, which application isincorporated herein by reference. The crown ethers described thereincontain at least four oxygen heteroatoms each separated from the otherby at least two aliphatic carbon atoms in series. These crown ethersinclude [18]-crown-6 and [15]-crown-5.

The preferred co-solvents include tetraglyme and [18]-crown-6

This ratio of the substituted-gamma-butyrolactone solvent to co-solvent,hereafter referred to as the "solvent ratio," may range from 1 to 20 to50 to 1, determined on a volume basis. However, it is to be emphasizedthat in any reaction system, such factors as the ratio of carbonmonoxide to hydrogen, temperature and pressure selected, concentrationsof added components such as catalysts and promoters, the nature of thepromoter, play a role in determining what solvent ratio is mosteffective. When selecting the appropriate solvent ratio one will berequired to explore in a number of experiments in a given reactionsystem, a number of ratios such that the optimum solvent ratios can bedetermined.

The rhodium carbonyl complex catalysts suitable for use herein may be inthe form of rhodium carbonyl clusters. P. Chini, in a review articleentitled "The Closed Metal Carbonyl Clusters" published in Review(1968), Inorganica Chimica Acta, pages 30-50, states that a metalcluster compound is "a finite group of metal atoms which are heldtogether entirely, mainly, or at least to a significant extent by bondsdirectly between the metal atoms even though some non-metal atoms may beassociated intimately with the cluster." The rhodium carbonyl clusterscontain rhodium bonded to rhodium or rhodium bonded to another metal,such as cobalt and/or iridium. The preferred rhodium carbonyl clustercompounds are those which contain rhodium-rhodium bonds. These compoundsdesirably contain carbon and oxygen in the form of carbonyl (--CO), inwhich the carbonyl may be "terminal", "edge-bridging", and/or"face-bridging". They may also contain hydrogen and carbon in formsother than carbonyl. The structure of two distinct rhodium carbonylclusters having the formula Rh₆ (CO)₁₆ and Rh₁₂ (CO)₃₀ ²⁻, and bothsuitable for use in this invention are shown, for example, in U.S. Pat.No. 3,957,857.

The structures of the rhodium carbonyl clusters may be ascertained byX-ray crystal diffraction, nuclear magnetic resonance (NMR) spectra, orinfrared spectra as disclosed in the article entitled "Synthesis andProperties of the Derivatives of the [Rh₁₂ (CO)₃₀ ]²⁻ Anion" by P. Chiniand S. Martinengo; appearing in Inorganica Chimica Acta, 3:2 pp299-302,June (1969). Of particular analytical utility in the present inventionis the use of infrared spectroscopy which allows for characterization ofthe particular rhodium carbonyl complex present during the operation ofthe process of the present invention.

A number of nitrogen and/or oxygen-containing bases may be used in theprocess of the present invention. For the purposes of this invention,the bases can be considered to promote the activity of the rhodiumcatalysts.

Nitrogen Lewis bases used as promoters generally contain hydrogen andnitrogen atoms. They may also contain carbon and/or oxygen atoms. Theymay be organic or inorganic compounds. With respect to the organiccompounds, the carbon atoms can be part of an acyclic and/or cyclicradical such as aliphatic, cycloaliphatic, aromatic (including fused andbridged) carbon radicals, and the like. Preferably, the organic Lewisbases contain from 2 to 60, most preferably 2 to 40 carbon atoms. Thenitrogen atoms can be in the form of imino(--N=), amino (--N--), nitrilo(N.tbd.), etc. Desirably, the Lewis base nitrogen atoms are in the formof imino nitrogen and/or amino nitrogen. The oxygen atoms can be in theform of groups such as hydroxyl (aliphatic or phenolic), carboxyl##STR5## carbonyloxy ##STR6## oxy (--O--), carbonyl ##STR7## etc., allof said groups containing Lewis base oxygen atoms. In this respect, itis the "hydroxyl" oxygen in the ##STR8## and the "oxy" oxygen in the##STR9## that are acting as Lewis base atoms. The organic Lewis basesmay also contain other atoms and/or groups as substituents of theaforementioned radicals, such as alkyl, cycloalkyl, aryl, chloro,trialkylsilyl substituents.

Illustrative of organic aza-oxa Lewis bases are, for example, thealkanolamines, such as, ethanolamine, diethanolamine, isopropanolamine,di-n-propanolamine, and the like; N,N-dimethylglycine,N,N-diethylglycine; iminodiacetic acid, N-methyliminodiacetic acid;N-methyldiethanolamine; 2-hydroxypyridine, 2,4-dihydroxypyridine,2-methoxypyridine, 2,6-dimethoxypyridine, 2-ethoxypyridine; lower alkylsubstituted hydroxypyridines, such as 4-methyl-2-hydroxypyridine,4-methyl-2,6-dihydroxypyridine, and the like; morpholine, substitutedmorpholines, such as 4-methylmorpholine, 4-phenylmorpholine; picolinicacid, methyl-substituted picolinic acid; nitrilotriacetic acid,2,5-dicarboxypiperazine, N-(2-hydroxyethyl) iminodiacetic acid,ethylenediaminetetraacetic acid; 2,6-dicarboxypyridine;8-hydroxyquinoline, 2-carboxyquinoline,cyclohexane-1,2-diamine-N,N,N',N'-tetraacetic acid, the tetramethylester of ethylenediaminetetraacetic acid, and the like.

Other Lewis base nitrogen containing compounds include organic andinorganic amines.

Illustrative of such inorganic amines are, e.g., ammonia, hydroxylamine,and hydrazine. Primary, secondary, or tertiary organic amines arepromoters. This includes the mono- and polyamines (such as di-, tri-,tetraamines, etc.) and those compounds in which the Lewis base nitrogenforms part of a ring structure as in pyridine, quinoline, pyrimidinemorpholine, hexamethylenetetraamine, and the like. In addition anycompounds capable of yielding an amino nitrogen under the reactionconditions of the present invention are promoters, as in the case of anamide, such as formamide, cyanamide, and urea, or an oxime. Furtherillustrative of Lewis base nitrogen compounds are aliphatic amines suchas methylamine, ethylamine, n-propylamine, isopropylamine, octylamine,dodecylamine, dimethylamine, diethylamine, diisoamylamine,methylethylamine, diisobutylamine, trimethylamine, methyldiethylamine,triisobutylamine, tridecylamine, and the like; aliphatic and aromaticdi- and polyamines such as 1,2-ethanediamine, 1,3-propanediamine,N,N,N',N'-tetramethylenediamine, N,N,N',N'-tetraethylethylenediamine,N,N,N',N'-tetra-n-propylethylenediamine,N,N,N',N'-tetrabutylethylenediamine, o-phenylenediamine,m-phenylenediamine, p-phenylenediamine, p-tolylenediamine, o-tolidene,N,N,N',N'-tetramethyl-p-phenylenediamine,N,N,N',N'-tetraethyl-4,4'-biphenyldiamine, and the like; aromatic aminessuch as aniline, 1-naphthylamine, 2-naphthylamine, p-toluidine,o-3-xylidine, p-2-xylidine, benzylamine, diphenylamine, dimethylaniline,diethylaniline, N-phenyl-1-naphthylamine,bis-(1,8)-dimethylaminonaphthalene, and the like; alicyclic amines suchas cyclohexylamine, dicyclohexylamine, and the like; heterocyclic aminessuch as piperidine; substituted piperidines such as 2-methylpiperidine,3-methylpiperidine, 4-ethylpiperidine, and 3-phenylpiperidine; pyridine;substituted pyridines such as 2-methylpyridine, 2-phenylpyridine,2-methyl-4-ethylpyridine, 2,4,6-trimethylpyridine, 2-dodecylpyridine,2-chloropyridine, and 2-(dimethylamino) pyridine; quinoline; substitutedquinolines, such as 2-(dimethylamino)-6-methoxyquinoline;4,5-phenanthroline; 1,8-phenanthroline; 1,5-phenanthroline; piperazine;substituted piperazines such as N-methylpiperazine, N-ethylpiperazine,2-methyl-N-methylpiperazine; 2,2'dipyridyl, methyl-substituted2,2-dipyridyl; ethyl-substituted 2,2'-dipyridyl;4-triethylsilyl-2,2'-dipyridyl; 1,4-diazabicyclo[2.2.2]octane, methylsubstituted 1,4-diazabicyclo [2.2.2]octane, purine and the like.

Also included herein are the use of dimorpholine compounds characterizedby the formula: ##STR10## wherein R is divalent alkylene of 1 to about30 carbon atoms and 1,4-phenylene.

The base provided to the reaction mixture is present in an amount whichis equal to or greater than that amount, determined from the basesbasicity, which achieves the optimum rate of formation of said alkanepolyol at said correlated catalyst concentration, temperature andpressure of such reaction mixture.

The concentration of the base will typically be within about 0.001 toabout 10 molar. Obviously this range is definitive of the potentialscatter of concentrations predicated on the varieties of the basicitiesof the bases available.

Under reaction conditions the base is preferably used in amounts fromabout 0.02 to about 40 equivalents of base, most preferably from about0.1 to about 20 equivalents base, for every atom of rhodium in thereaction mixture. The number of equivalents of base is equal to thenumber of molecules of base times the number of nitrogen atoms in eachmolecule.

In practicing the method of the present invention, the synthesis of thedesired alkane diols and derivatives thereof, by the reaction ofhydrogen with an oxide of carbon is suitably conducted under operativeconditions, as heretofore described, which give reasonable reactionrates and/or conversions.

The process is suitably effected over a wide superatmospheric pressurerange of from about 800 psia to about 50,000 psia. Pressures as high as50,000 psia, and higher can be employed but with no apparent advantagesattendant thereto which offset the unattractive plant investment outlayrequired for such high pressure equipment. Therefore, the upper pressurelimitation is desirably approximately 16,000 psia. Effecting the presentprocess below about 16,000 psia, especially below about 13,000 psia, andpreferably at pressures below about 8000 psia, results in costadvantages which are associated with low pressure equipmentrequirements. In attempting to foresee a commercial operation of thisprocess, pressures between about 4,000 psia and 16,000 psia appear torepresent most realistic values.

In a preferred embodiment of the present invention the pressuresreferred to above represent the total pressures of hydrogen and oxidesof carbon in the reactor.

The process of this invention can also be carried out by providing saltsin the homogeneous liquid phase reaction mixture. Suitable salts includeany organic or inorganic salt which does not adversely affect theproduction of polyhydric alcohols. Experimental work suggest that anysalt is beneficial as either a copromoter and/or in aiding inmaintaining rhodium in solution during the reaction. Illustrative of thesalts useful in the practice of the present invention are the ammoniumsalts and the salts of the metals of Group I and Group II of thePeriodic Table (Handbook of Chemistry and Physics - 50th Edition) forinstance the halide, hydroxide, alkoxide, phenoxide and carboxylatesalts such as sodium fluoride, cesium fluoride, cesium pyridinolate,cesium formate, cesium acetate, cesium benzoate, cesiump-methylsulfonylbenzoate (CH₃ SO₂ C₆ H₄ COO)Cs, rubidium acetate,magnesium acetate, strontium acetate, ammonium formate, ammoniumbenzoate and the like. Preferred are the cesium, rubidium, potassium,and ammonium salts.

Also useful in the practice of the present invention are organic saltsof the following formula: ##STR11## wherein R₁ through R₆ in formulas(II) and (III) above are any organic radicals which do not adverselyaffect the production of polyhydric alcohols by reacting oxides ofcarbon with hydrogen in the presence of the aforedefined rhodiumcarbonyl complex, such as a straight or branched chain alkyl group,having from 1 to 20 carbon atoms in the alkyl chain, such as methyl,ethyl, n-propyl, isopropyl, n-butyl, octyl, 2-ethylhexyl, dodecyl, andthe like; or a cycloaliphatic group including the monocyclic andbicyclic groups cyclopentyl, cyclohexyl, and bicyclo[2.2.1]heptylgroups, and the like or an aryl, alkylaryl, or aralkyl group such asphenyl, naphthyl, xylyl, tolyl, t-butylphenyl, benzyl, beta-phenylethyl,3-phenylpropyl and the like; or a functionally substituted alkyl such asbeta-hydroxyethyl, ethoxymethyl, ethoxyethyl, phenoxyethyl, and thelike; or a polyalkylene ether group of the formula (C_(n) H_(2n) O)_(x)--OR wherein n has an average value from 1 to 4, x has an average valuefrom 2 to about 150, and R may be hydrogen or alkyl of 1 to about 12carbon atoms. Illustrative of such polyalkylene ether groups arepoly(oxyethylene), poly(oxypropylene), poly(oxyethyleneoxypropylene),poly(oxyethyleneoxybutylene), and the like. Y in formulas I and II abovemay be any anion which does not adversely affect the production ofpolyhydric alcohols in the practice of the present invention such ashydroxide; a halide, for instance fluoride, chloride, bromide andiodide; a carboxylate group, such as formate, acetate, propionate, andbenzoate and the like; an alkoxide group such as methoxide, ethoxide,phenoxide, and the like; a functionally substituted alkoxide orphenoxide group such as methoxyethoxide, ethoxyethoxide, phenoxyethoxideand the like; a pyridinolate or quinolate group; and others. PreferablyY in formulas I and II, above, is a carboxylate, most preferablyformate, acetate and benzoate.

A suitable method for preparing the bis(triorganophosphine) iminiumsalts is disclosed in an article by Appel, R. and Hanas, A. appearing inZ. Anorg. u. Allg. Chem., 311, 290, (1961).

Other organic salts useful in the practice of the present inventioninclude the quaternized heterocyclic amine salts such as the pyridinium,piperidinium, morpholinium, quinolinium salts and the like, e.g.,N-ethylpyridinium fluoride, N-methylmorpholinium benzoate,N-phenylpiperidinium hydroxide, N,N'-dimethyl-2,2-bipyridinium acetate,and the like.

In addition, the anion of the above salt may be any of the rhodiumcarbonyl anions. Suitable rhodium carbonyl anions include [Rh₆ (CO)₁₅]²⁻ ; [Rh₆ (CO)₁₅ Y]⁻ wherein Y may be halogen, such as chlorine,bromine, or iodine, [Rh₆ (CO)₁₅ (COOR"]⁻ wherein R" is lower alkyl oraryl such as methyl, ethyl, or phenyl; [Rh₆ (CO)₁₄ ]²⁻ ; [Rh₇ (CO)₁₆ ]³⁻; [Rh₁₂ (CO)₃₀ ]²⁻ ; Rh₁₃ (CO)₂₄ H₃ ⁻² ; and Rh₁₃ (CO)₂₄ H₂ ⁻³.

Under reaction conditions where a salt is employed the salt is desirablyadded with the initial charge of reactants in amounts of from about 0.5to about 2.0 moles, preferably from about 0.8 to about 1.6 moles, andmost preferably from about 0.9 to 1.4 moles of salt for every five atomsof rhodium present in the reaction mixture.

The temperature which may be employed can vary over a wide range ofelevated temperatures. In general, the process can be conducted at atemperature in the range of from about 100° C. and upwards toapproximately 375° C., and higher. Temperatures outside this statedrange are not excluded from the scope of the invention. At the lower endof the temperature range, and lower, the rate of reaction to desiredproduct becomes markedly slow. At the upper temperature range, andbeyond, signs of some catalyst instability are noted. Notwithstandingthis factor, reaction continues and alkane polyols and/or theirderivatives are produced. Additionally, one should take notice of theequilibrium reaction for forming ethylene glycol

    2CO+3H.sub.2 ⃡HOCH.sub.2 CH.sub.2 OH

At relatively high temperatures the equilibrium increasingly favors theleft hand side of the equation. To drive the reaction to the formationof increased quantities of ethylene glycol, higher partial pressures ofcarbon monoxide and hydrogen are required. Processes based oncorrespondingly higher pressures, however, do not represent preferredembodiments of the invention in view of the high investment costsassociated with erecting chemical plants which utilize high pressureutilities and the necessity of fabricating equipment capable ofwithstanding such enormous pressures. Suitable temperatures are betweenabout 150° C. to about 350° C., and desirably from about 210° C. toabout 320° C.

The process is effected for a period of time sufficient to produce thealkane polyols and/or derivatives thereof. In general, the residencetime can vary from minutes to several hours, e.g., from a few minutes toapproximately 24 hours, and longer. It is readily appreciated that theresidence period will be influenced to a significant extent by thereaction temperature, the concentration and choice of the catalyst, thetotal gas pressure and the partial pressures exerted by its components,the concentration and choice of diluent, and other factors. Thesynthesis of the desired product(s) by the reaction of hydrogen with anoxide of carbon is suitably conducted under operative conditions whichgive reasonable reaction rates and/or conversions.

The relative amounts of oxide of carbon and hydrogen which are initiallypresent in the reaction mixture can be varied over a wide range. Ingeneral, the mole ratio of CO:H₂ is in the range of from about 20:1 toabout 1:20, suitably from about 10:1 to about 1:10, and preferably fromabout 5:1 to about 1:5.

It is understood, however, that molar ratios outside the aforesaid broadrange may be employed. Substances or reaction mixtures which give riseto the formation of carbon monoxide and hydrogen under the reactionconditions may be employed instead of mixtures comprising carbonmonoxide and hydrogen which are used in preferred embodiments in thepractice of the invention. For instance, polyhydric alcohols areobtained by using mixtures containing carbon dioxide and hydrogen.Mixtures of carbon dioxide, carbon monoxide and hydrogen can also beemployed. If desired, the reaction mixture can comprise steam and carbonmonoxide.

The process can be executed in a batch, semi-continuous, or continuousfashion. The reaction can be conducted in a single reaction zone or aplurality of reaction zones, in series or in parallel, or it may beconducted intermittently or continuously in an elongated tubular zone orseries of such zones. The material of construction should be such thatit is inert during the reaction and the fabrication of the equipmentshould be able to withstand the reaction temperature and pressure. Thereaction zone can be fitted with internal and/or external heatexchanger(s) to thus control undue temperature fluctuations, or toprevent any possible "run-away" reaction temperatures due to theexothermic nature of the reaction. In preferred embodiments of theinvention, agitation means to vary the degree of mixing of the reactionmixture can be suitably employed. Mixing induced by vibration, shaker,stirrer, rotatory, oscillation, ultrasonic, etc., are all illustrativeof the types of agitation means which are contemplated. Such means areavailable and well-known to the art. The catalyst may be initiallyintroduced into the reaction zone batchwise, or it may be continuouslyor intermittently introduced into such zone during the course of thesynthesis reaction.

Means to introduce and/or adjust the reactants, either intermittently orcontinuously, into the reaction zone during the course of the reactioncan be conveniently utilized in the novel process especially to maintainthe desired molar ratios of and the partial pressures exerted by thereactants.

The operative conditions can be adjusted to optimize the conversion ofthe desired product and/or the economics of the process. In a continuousprocess, for instance, when it is preferred to operate at relatively lowconversions, it is generally desirable to recirculate unreactedsynthesis gas with/without make-up carbon monoxide and hydrogen to thereaction. Recovery of the desired product can be achieved by methodswell-known in the art such as by distillation, fractionation,extraction, and the like. A fraction comprising rhodium catalyst,generally contained in byproducts and/or normally liquid organicdiluent, can be recycled to the reaction zone, if desired. All or aportion of such fraction can be removed for recovery of the rhodiumvalues or regeneration to the active catalyst and intermittently addedto the recycle stream or directly to the reaction zone.

The active forms of the rhodium carbonyl clusters may be prepared byvarious techniques. They can be preformed and then introduced into thereaction zone or they can be formed in situ.

The equipment arrangement and procedure which provides the capabilityfor determining the existence of anionic rhodium carbonyl complexes orclusters having defined infrared spectrum characteristics, during thecourse of the manufacture of polyhydric alcohols from carbon monoxideand hydrogen, pursuant to this invention is disclosed and schematicallydepicted in U.S. Pat. No. 3,957,857 the disclosure of which isincorporated herein by reference.

A particularly desirable infrared cell construction is described in U.S.Pat. No. 3,886,364, issued May 27, 1975, and its disclosure of apreferred cell construction is incorporated herein by reference.

The "oxide of carbon" as covered by the claims and as used herein isintended to mean carbon monoxide and mixtures of carbon dioxide andcarbon monoxide, either introduced as such or formed in the reaction.

The following examples are merely illustrative and are not presented asa definition of the limits of the invention:

EXAMPLES 1 TO 21

A 150 ml. capacity stainless steel reactor capable of withstandingpressures up to 7,000 atmospheres was charged with a premix of 75 cubiccentimeters (cc) of the indicated solvent(s), the indicated amount(mmoles) of rhodium dicarbonylacetylacetonate, and promoter(s). Thereactor was sealed and charged with a gaseous mixture, containing equalmolar amounts of carbon monoxide and hydrogen to a pressure in poundsper square inch (psig) as set forth in the Table. Heat was applied tothe reactor and its contents; when the temperature of the mixture insidethe reactor reached the temperature (in °C.) as set forth in the Tableand as measured by a suitably placed thermocouple, an additionaladjustment of carbon monoxide and hydrogen (H₂ :CO)=1:1 mole ratio wasmade to bring the pressure back to the pressure reported in the Table.Additional carbon monoxide and hydrogen was added whenever the pressureinside the reactor dropped below about 7500 psig. With these addedrepressurizations, the pressure (psig±400 psig) inside the reactor wasmaintained over the entire reaction period.

After the reaction period, the vessel and its contents were cooled toroom temperature, the excess gas vented and the reaction product mixturewas removed. Analysis of the reaction product mixture was made by gaschromatographic analysis using a Hewlett Packard FM^(TM) model 810Research Chromatograph.

Rhodium recovery was determined by atomic absorption analysis of thecontents of the reactor after the venting of the unreacted gases at theend of the reaction.

An atomic absorption analysis for rhodium was run on the reactor'scontents. The rhodium recovery values recited below are the percentrhodium based on the total rhodium charged to the reactor that issoluble or suspended in the reaction mixture after the specifiedreaction time. The results are set forth in the Table.

Also, the percent decrease of the quantity of2,2-dimethyl-gamma-butyrolactone and gamma-butyrolactone, each relativeto tetraglyme, is set forth in the Table.

                                      TABLE                                       __________________________________________________________________________                                                             % De-                                                                         crease                                                                        of the ratio                                                      (Mole       of the                  Solvent.sup.(a)                           Liter.sup.-1                                                                          Rh  butyrolac-              (Volume/                                                                            Pressure                                                                           Temp.       Amine                                                                              Rh(CO).sub.2 acac.sup.(c)                                                             Rate  Hour.sup.-1)                                                                          Recov-                                                                            tone to              Ex.                                                                              Volume)                                                                             (psig)                                                                             (°C.)                                                                      Salt.sup.(b) (mmoles)                                                                 (mmoles)                                                                           (mmoles)                                                                              CH.sub.3 OH                                                                         HOCH.sub.2 CH.sub.2 OH                                                                ery tetraglyme           __________________________________________________________________________    1  TG    8000 240 PhCO.sub.2 Cs                                                                         --   3       0.45  0.31    27                                         (0.65)                                                      2  γ-B                                                                           8000 240 "       --   3       0.59  0.57    85                       3  DM-B  8000 240 "       --   3       0.59  0.65    81                       4  TG    12,500                                                                             250 PhCO.sub.2 Cs                                                                         Pyridine                                                                           3       3.2   3.0     79                                         (0.75)  (1.25)                                              5  TG/γ-B                                                                        12,500                                                                             250 "       "    3       4.8   3.3     102                         (57/18)                                                                    6  TG/DM-B                                                                             12,500                                                                             250 "       "    3       3.3   3.3     102                         (57/18)                                                                    7  TG    15,000                                                                             260 "       "    3       9.3   5.7     90                       8  TG/γ-B                                                                        15,000                                                                             260 "       "    3       ˜7.3,˜4.9                                                               8.5,7.8 103,102                                                                           7.6 in 31 min           (57/18)                                                                    9  TG/DM-B                                                                             15,000                                                                             260 "       "    3       ˜3.9                                                                          8.0     107 3.9 in 31 min           (57/18)                                                                    10 CR    15,000                                                                             270 PhCO.sub.2 Cs                                                                         --   1.5     6.4,7.4                                                                             6.7,7.5 87,87                                      (0.50)                                                      11 CR/γ-B                                                                        15,000                                                                             270 "       --   1.5     8.0   10.4    110                         (57/18)                                                                    12 CR/DM-B                                                                             15,000                                                                             270 "       --   1.5     ˜6.3                                                                          9.5     94                          (57/18)                                                                    13 TG    8,000                                                                              240 PhCO.sub.2 Cs                                                                         --   3.0     0.45  0.31    27                                         (0.65)                                                      14 TG/γ-B                                                                        8,000                                                                              240 "       --   3.0     ˜0.54                                                                         0.66    89  1.5 in 4 hrs.           (48/27)                                                                    15 TG/DM-B                                                                             8,000                                                                              240 "       --   3.0     ˜0.60                                                                         0.68    88  0.2 in 4 hrs.           (48/27)                                                                    16 TG    8000 240 PhCO.sub.2 Cs                                                                         --   1.5     0.40  0.29    9   '                                      (0.325)                                                     17 TG/γ-B                                                                        8000 240 "       --   1.5     0.41  0.53    50  7.4 in 12 hr.           (48/27)                                                                    18 TG/DM-B                                                                             8000 240 "       --   1.5     0.42  0.41    45  1.4 in 12 hr.           (48/27)                                                                    19 TG    12,500                                                                             250 PhCO.sub.2 Cs                                                                         Pyridine                                                                           0.5     0.62  0.72    8                                          (0.13)  (0.4)                                               20 TG/γ-B                                                                        12,500                                                                             250 "       "    0.5     1.3   2.9     72  17 in                   (57/18)                                               10.3 hr.             21 TG/DM-B                                                                             12,500                                                                             250 "       "    0.5     1.6   3.1     62  4.6 in                  (57/18)                                               10.3                 __________________________________________________________________________                                                             hr.                   .sup.(a) TG:tetraglyme; γB=butyrolactone;                               DMB=dimethylgamma-butyrolactone; CR=[18crown-6                                .sup.(b) PhCO.sub.2 Cs: cesium benzoate?                                      .sup.(c) Rh(CO).sub.2 acac: rhodium dicarbonylacetylacetonate                 .sup.(d) Scaled proportionately to 6mmoles of Rh(CO).sub.2 acac          

What is claimed is:
 1. The process for producing polyhydric alcohol(s)which comprises reacting hydrogen and oxides of carbon in a solventcomprising a 2,2-di(alkyl)-gamma-butyrolactone wherein the alkyl groupshave from 1 to 12 carbon atoms, in the presence of a rhodium carbonylcomplex at a temperature of between about 100° C. and 375° C. and apressure of between about 1000 psia. and 50,000 psia. to produce saidpolyhydric alcohol(s).
 2. The process of claim 1 wherein the temperatureof the reaction is between about 150° C. and 320° C.
 3. The process ofclaim 2 wherein the temperature of the reaction is between about 190° C.and 290° C.
 4. The process of claim 1 wherein the pressure of thereaction is between about 1000 psia and 25,000 psia.
 5. The process ofclaim 4 wherein the pressure of the reaction is between about 1000 psiaand 17,000 psia.
 6. The process of claim 1 wherein the2,2-di-(alkyl)-gamma-butyrolactone is 2,2-dimethyl-gamma-butyrolactone.7. The process of claim 1 wherein the solvent is employed with aco-solvent.
 8. The process of claim 7 wherein the cosolvent issulfolane.
 9. The process of claim 7 wherein the cosolvent istetraglyme.
 10. The process of claim 7 wherein the cosolvent is a crownether.
 11. The process of claim 10 wherein the crown ether is[18]-crown-6.
 12. The process of claim 1 wherein the alkane polyol isethylene glycol.
 13. The process of claim 1 wherein the principalproducts recovered are ethylene glycol and methanol.